Steven Moffat Leaving ‘Doctor Who’ in 2017

After six seasons of overseeing the exploits of a centuries-old alien adventurer, Steven Moffat plans to move on to other parts of the space-time continuum.

Mr. Moffat, the lead writer and an executive producer of “Doctor Who,” the popular BBC science-fiction series (which is shown in the United States on BBC America), said on Friday that he was stepping down in 2017, after the tenth season of the current version of the show.

“Feels odd to be talking about leaving when I’m just starting work on the scripts for Season 10,” Mr. Moffat said in a statement provided by BBC America, “but the fact is my timey-wimey is running out.”

Mr. Moffat, who has been writing for “Doctor Who” since it was resuscitated for television in 2005, became the show runner in its fifth season in 2010. Under his tenure, the series introduced the actor Matt Smith in the role of the enigmatic time traveler known as the Doctor, and saw Mr. Smith succeeded in the role by Peter Capaldi.

Mr. Moffat, who is also a creator of “Sherlock,” a modern-day TV retelling of Shelock Holmes, will be followed at “Doctor Who” by Chris Chibnall, a creator of the crime drama “Broadchurch.”

BBC America said it will show a new “Doctor Who” Christmas special in 2016, followed by Mr. Moffat’s final season in 2017 and Mr. Chibnall’s debut season in 2018.

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